This invention relates to optical devices, and more particularly to optical waveguide devices.
In the integrated circuit industry, there is a continuing effort to increase device speed and increase device densities. Optical systems are a technology that promise to increase the speed and current density of the circuits. Optical devices, such as optical modulators are used in these optical systems. Such optical modulators can be used to perform a variety of functions in integrated circuits such as signal transmission and attenuation. Optical modulators typically require different devices to phase modulate or amplitude modulate light.
Optical devices that perform different functions are typically formed and shaped differently in order to perform the different functions. As such, each type of optical device, and each size of the same optical device type, has to be manufactured distinctly. Therefore, the production of precision optical devices is expensive. Additionally, optical devices are susceptible to changes in temperature, contact, pressure, humidity, etc. As such, the optical devices are typically contained in packaging that maintains the conditions under which the optical devices are operating. Providing such packaging is extremely expensive. Even if such packaging is provided, passive optical devices may be exposed to slight condition changes. As such, the passive optical devices perform differently under the different conditions. The modulators will modulate the light a different amount. If the characteristics of a passive optical device is altered outside of very close tolerances, then the optical device will not adequately perform its function. In other words, there is no adjustability for passive optical devices.
It would therefore be desirable to provide an optical modulator that can both phase modulate and amplitude modulate, or a combination of the two, using the same device. Additionally, it would be desired to provide an optical device whose operation can be adjusted either to control the amount of modulation, or to compensate for changed parameters.
The present invention is directed to an apparatus and associated method for modulating the propagation constant of a region of modulating propagation constant in an optical waveguide. The method comprising positioning an electrode of a prescribed electrode shape proximate the waveguide. The region of modulating propagation constant is projected into the waveguide and corresponds, in shape, to the prescribed electrode shape by applying a voltage to the shaped electrode. The propagation constant of the region of modulating propagation constant is controlled by varying the voltage.